Copolymers including ultraviolet absorbing groups and fluoropolymer compositions including them

ABSTRACT

A thermoplastic copolymer that includes a first divalent unit having a pendent ultraviolet absorbing group and a second divalent unit that is fluorinated. A fluoropolymer composition including the thermoplastic copolymer is also disclosed.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national stage filing under 35 U.S.C. 371 ofPCT/US2013/076840, filed Dec. 20, 2013, which claims priority to U.S.Provisional Application No. 61/740,125, filed Dec. 20, 2012, thedisclosure of which is incorporated by reference in its entirety herein.

BACKGROUND

Fluoropolymers are known to have a variety of useful properties,including cleanability, weather resistance, and chemical resistance.Such beneficial properties render fluoropolymers useful, for example,for a variety of outdoor applications including signage, films orcoatings for architectural coverings, and protective coverings forphotovoltaic modules.

It may be desirable to incorporate ultraviolet absorbers (UVAs) intomaterials exposed to ultraviolet (UV) radiation, for example, to protecta topcoat or topsheet or an underlying substrate or adhesive from UVdegradation. Some UVAs can be dispersed into some compositions, butsometimes they can be lost due to volatilization or migration to thesurface. Covalent incorporation of UVAs into certain compositions hasbeen proposed. See, e.g., U.S. Pat. Appl. Pub. No. 2011/0297228 (Li etal.).

It has been reported that common UVAs can be incompatible withfluoropolymers. See, e.g., U.S. Pat. No. 6,251,521 (Eian et al.). Thisincompatibility can lead to degradation of physical or opticalproperties (e.g., loss of clarity or increased fogginess) as well asincreased or accelerated loss of the UVA by migration, bleeding, orblooming.

SUMMARY

The present disclosure provides a copolymer that includes a firstdivalent unit with a pendent ultraviolet absorbing group and a seconddivalent unit that is fluorinated. These copolymers are generally quitecompatible with fluoropolymers such that the copolymers andfluoropolymers are readily blended together. Compositions including thefluoropolymers and copolymers provide protection to ultraviolet lightand have good transparency to visible and infrared light. Theseproperties are typically well maintained even after accelerated UVexposure and exposure to high temperature and humidity conditions.

In one aspect, the present disclosure provides a copolymer that includesa first divalent unit having a pendent ultraviolet absorbing group and asecond divalent unit represented by formula:

In this formula, Rf represents a fluoroalkyl group having from 1 to 6carbon atoms optionally interrupted by one —O— group, or Rf represents apolyfluoropolyether group. R¹ is hydrogen or methyl. Q is a bond,—SO₂—N(R)—, or —C(O)—N(R)—, wherein R is alkyl having from 1 to 4 carbonatoms or hydrogen, and m is an integer from 0 to 11. The copolymer is athermoplastic copolymer.

In another aspect, the present disclosure provides a compositioncomprising a fluoropolymer and the copolymer in any of its embodimentsdescribed above or below.

In another aspect, the present disclosure provides a method of making acomposition. The method includes blending the copolymer in any of itsembodiments described above or below with a fluoropolymer to make thecomposition.

In another aspect, the present disclosure provides a method of making afilm. The method includes providing the composition in any of itsembodiments and extruding the composition into a film.

As described above, compositions including the fluoropolymers andcopolymers typically provide protection to ultraviolet light and havegood transparency to visible and infrared light. Accordingly, thepresent disclosure provides a photovoltaic device include thecomposition according to the present disclosure in any of itsembodiments.

In this application:

Terms such as “a”, “an” and “the” are not intended to refer to only asingular entity, but include the general class of which a specificexample may be used for illustration. The terms “a”, “an”, and “the” areused interchangeably with the term “at least one”.

The phrase “comprises at least one of” followed by a list refers tocomprising any one of the items in the list and any combination of twoor more items in the list. The phrase “at least one of” followed by alist refers to any one of the items in the list or any combination oftwo or more items in the list.

The term “ultraviolet absorbing group” refers to a covalently attachedultraviolet absorber (UVA). UVAs are known to those skilled in the artas being capable of dissipating absorbed light energy from UV rays asheat by reversible intramolecular proton transfer. UVAs are selectedsuch that the copolymer in any of the embodiments of copolymers orsecond copolymers disclosed herein absorbs at least 70%, 80%, or 90% ofincident light in a wavelength range from 180 nanometers (nm) to 400 nm.

“Alkyl group” and the prefix “alk-” are inclusive of both straight chainand branched chain groups and of cyclic groups. Unless otherwisespecified, alkyl groups herein have up to 20 carbon atoms. Cyclic groupscan be monocyclic or polycyclic and, in some embodiments, have from 3 to10 ring carbon atoms.

The phrase “interrupted by at least one —O— group”, for example, withregard to an alkyl (which may or may not be fluorinated), alkylene, orarylalkylene refers to having part of the alkyl, alkylene, orarylalkylene on both sides of the —O— group. For example,—CH₂CH₂—O—CH₂—CH₂— is an alkylene group interrupted by an —O—.

The term “fluoroalkyl group” includes linear, branched, and/or cyclicalkyl groups in which all C—H bonds are replaced by C—F bonds as well asgroups in which hydrogen or chlorine atoms are present instead offluorine atoms. In some embodiments, up to one atom of either hydrogenor chlorine is present for every two carbon atoms.

The term “polymer” refers to a molecule having a structure whichessentially includes the multiple repetition of units derived, actuallyor conceptually, from molecules of low relative molecular mass. The term“polymer” encompasses oligomers.

All numerical ranges are inclusive of their endpoints and nonintegralvalues between the endpoints unless otherwise stated.

DETAILED DESCRIPTION

Copolymers according to the present disclosure are linear or branchedcopolymers. Typically, they are linear copolymers. They may be randomcopolymers or block copolymers. They are not covalently crosslinked, andtherefore may be considered thermoplastic. Accordingly, they may bedissolved in solvents and have measurable molecular weights as opposedto covalently crosslinked polymers, which cannot be dissolved insolvents and molecular weights approaching infinity. Thermoplastics arealso typically melt-processable such as by an extrusion process.Copolymers according to the present disclosure typically have weightaverage molecular weights in a range from 1000 grams per mole to 100,000grams per mole. In some embodiments, the weight average molecular weightis at least 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10000grams per mole up to 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, orup to 90,000 grams per mole. In some embodiments, the copolymer has anumber average molecular weight of up to 50,000 grams per mole. In theseembodiments, the copolymer can be considered an oligomer. In some ofthese embodiments, the copolymer has a number average molecular weightof up to 40,000, 30,000, 20,000, or less than 20,000 grams per mole(e.g., up to 19,500, 19,000, or 18,500 grams per mole). In any of theembodiments in which the copolymer is an oligomer, its number averagemolecular weight may be greater than 5,000 grams per mole or greaterthan 7,500 grams per mole. Copolymers disclosed herein typically have adistribution of molecular weights and compositions. Weight and numberaverage molecular weights can be measured, for example, by gelpermeation chromatography (i.e., size exclusion chromatography) usingtechniques known to one of skill in the art.

Copolymers according to the present disclosure in any of theirembodiments include a first divalent unit comprising a pendentultraviolet absorbing (UVA) group. Any class of UVA may be useful forproviding the UVA group. Examples of useful classes includebenzophenones, benzotriazoles, triazines, cinnamates, cyanoacrylates,dicyano ethylenes, salicylates, oxanilides, and para-aminobenzoates. Insome embodiments, the pendent ultraviolet absorbing group comprises atriazine, a benzophenone, or a benzotriazole. In some embodiments, thependent ultraviolet absorbing group is a triazine. In some embodiments,the pendent ultraviolet absorbing group has enhanced spectral coveragein the long-wave UV region (e.g., 315 nm to 400 nm), enabling it toblock the high wavelength UV light that can cause yellowing in polymers.The first divalent unit can be considered to be a repeating unit in thecopolymer disclosed herein. The first divalent unit may be representedby formula -[—CH₂—C(H)UVA-]-, -[—CH₂—C(H)C(O)—O—X-UVA-]-,-[—CH₂—C(H)C(O)—NH—X—UVA-]-, -[—CH₂—C(CH₃)C(O)—O—X—UVA-]-, or-[—CH₂—C(CH₃)C(O)—NH—X—UVA-]-, wherein X is an alkylene or alkyleneoxygroup having from 1 to 10 (in some embodiments, 2 to 6 or 2 to 4) carbonatoms and optionally interrupted by one or more —O— groups andoptionally substituted by a hydroxyl group, and wherein UVA includes anyof the above embodiments of UVA groups. In the alkyleneoxy group, theoxygen is attached to the UVA group. The copolymer may include (e.g., atleast 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or at least 20 up to 30, 35, 40,45, 50, 100, or up to 200) of these repeating units. The repeating unitcan be derived from a substituted vinyl, substituted acrylate, orsubstituted methacrylate group.

In some embodiments, the first divalent unit is represented by formula:

wherein R¹ is hydrogen or methyl, V is O or NH, X is alkylene oralkyleneoxy group having from 1 to 10 (in some embodiments, 2 to 6 or 2to 4) carbon atoms and optionally interrupted by one or more —O— groupsand optionally substituted by a hydroxyl group, R is alkyl (e.g., havingfrom one to four carbon atoms), n is 0 or 1, and Z is a benzoyl group, a4,6-bisphenyl[1,3,5]triazin-2-yl group, or a 2H-benzotriazol-2-yl group,wherein the benzoyl group, 4,6-bisphenyl[1,3,5]triazin-2yl group, and2H-benzotriazol2-yl group is optionally substituted by one or morealkyl, aryl, alkoxy, hydroxyl, or halogen substituents, or a combinationof these substituents. In some embodiments, the alkyl and/or alkoxysubstituent independently has 1 to 4 or 1 to 2 carbon atoms. In someembodiments, each halogen substituent is independently a chloro, bromo,or iodo group. In some embodiments, each halogen substituent is a chlorogroup. The term “aryl” as used herein includes carbocyclic aromaticrings or ring systems, for example, having 1, 2, or 3 rings andoptionally containing at least one heteroatom (e.g., O, S, or N) in thering. Examples of aryl groups include phenyl, naphthyl, biphenyl,fluorenyl as well as furyl, thienyl, pyridyl, quinolinyl, isoquinolinyl,indolyl, isoindolyl, triazolyl, pyrrolyl, tetrazolyl, imidazolyl,pyrazolyl, oxazolyl, and thiazolyl. In the alkyleneoxy group, the oxygenis attached to the substituted benzene ring. In some embodiments, each Vis O and X is ethylene, propylene, butylene, ethyleneoxy, propyleneoxy,or butyleneoxy, with the oxygen attached to the substituted benzenering. In some embodiments, n is 0. In some embodiments, R is methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, or t-butyl, andn is 1. In some embodiments, Z is an unsubstituted benzoyl group. Insome embodiments, Z is 4,6-bis(2,4-dimethylphenyl)[1,3,5]triazin-2-yl;4,6-bis(2,4-diethylphenyl)[1,3,5]triazin-2-yl;4,6-bis(2,4-dimethoxyphenyl)[1,3,5]triazin-2-yl; or4,6-bis(2,4-diethoxyphenyl)[1,3,5]triazin-2-yl. In some embodiments, Zis 2H-benzotriazol-2-yl or 5-chloro-2H-benzotriazol-2-yl.

Copolymers disclosed herein in any of their embodiments include (e.g.,at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or at least 20 up to 30, 35,40, 45, 50, 100, or up to 200) second divalent units independentlyrepresented by formula:

For divalent units having this formula, Q is a bond, —SO₂N(R)—, or—C(O)—N(R)— wherein R is alkyl having 1 to 4 carbon atoms (e.g., methyl,ethyl, n-propyl, isopropyl, n-butyl, or isobutyl) or hydrogen. In someembodiments, Q is a bond. In some embodiments, Q is —SO₂N(R)—. In someof these embodiments, R is methyl or ethyl. m is an integer from 1 to 11(i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11). In some of theseembodiments, m is 1; in other of these embodiments, m is 2. In someembodiments wherein Q is —SO₂N(R)—, m is an integer from 2 to 11, 2 to6, or 2 to 4. In some embodiments wherein Q is a bond, m is an integerfrom 1 to 6, 1 to 4, or 1 to 2. In embodiments wherein Q is a bond, itshould be understood that the second divalent units may also berepresented by formula:

In some embodiments, copolymers disclosed herein, including any of theembodiments described above in connection to the first divalent units,comprise (e.g., at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or at least 20up 30, 35, 40, 45, 50, 100, or up to 200) second divalent unitsindependently represented by formula:

For divalent units of this formula, m′ is an integer from 2 to 11 (i.e.,2, 3, 4, 5, 6, 7, 8, 9, 10, or 11). In some embodiments, m′ is aninteger from 2 to 6 or 2 to 4. R³ is alkyl having 1 to 4 carbon atoms(e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, or isobutyl) orhydrogen. In some embodiments, R³ is methyl or ethyl.

For any of the embodiments of the second divalent units, each Rfindependently represents a fluorinated alkyl group having from 1 to 6(in some embodiments, 2 to 6 or 2 to 4) carbon atoms (e.g.,trifluoromethyl, perfluoroethyl, 1,1,2,2-tetrafluoroethyl,2-chlorotetrafluoroethyl, perfluoro-n-propyl, perfluoroisopropyl,perfluoro-n-butyl, 1,1,2,3,3,3-hexafluoropropyl, perfluoroisobutyl,perfluoro-sec-butyl, or perfluoro-tert-butyl, perfluoro-n-pentyl,pefluoroisopentyl, or perfluorohexyl). In some embodiments, Rf isperfluorobutyl (e.g., perfluoro-n-butyl, perfluoroisobutyl, orperfluoro-sec-butyl). In some embodiments, Rf is perfluoropropyl (e.g.,perfluoro-n-propyl or perfluoroisopropyl). The copolymer may include amixture of fluorinated monomers having different Rf fluoroalkyl groups(e.g., with an average of up to 6 or 4 carbon atoms).

In some embodiments, in copolymers disclosed herein, including any ofthe embodiments described above in connection to the first divalentunits, Rf is a polyfluoropolyether group. The term “polyfluoroether”refers to a compound or group having at least 3 (in some embodiments, atleast 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or even20) carbon atoms and at least 1 (in some embodiments, at least 2, 3, 4,5, 6, 7, or even 8) ether linkages, wherein hydrogen atoms on the carbonatoms are replaced with fluorine atoms. In some embodiments, Rf has upto 100, 110, 120, 130, 140, 150, or even 160 carbon atoms and up to 25,30, 35, 40, 45, 50, 55, or even 60 ether linkages.

In some embodiments, including embodiments wherein Rf is apolyfluoroether group, copolymers according to the present disclosurecomprise (e.g., at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or at least 20up 30, 35, 40, 45, 50, 100, or up to 200) second divalent unitsindependently represented by formula:

For divalent units of this formula, m′ is an integer from 2 to 11 (i.e.,2, 3, 4, 5, 6, 7, 8, 9, 10, or 11). In some embodiments, m′ is aninteger from 2 to 6 or 2 to 4. R⁴ is alkyl having 1 to 4 carbon atoms(e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, or isobutyl) orhydrogen. In some embodiments, R⁴ is methyl or ethyl. In someembodiments, R⁴ is hydrogen.

The polyfluoroether group Rf can be linear, branched, cyclic, orcombinations thereof and can be saturated or unsaturated.Polyfluoroether groups include those in which hydrogen or chlorine atomsare present instead of fluorine atoms with typically up to one atom ofeither hydrogen or chlorine is present for every two carbon atoms. Thecopolymer may include a mixture of fluorinated monomers having differentRf polyfluoroether groups. In some embodiments, the polyfluoroethergroup is a perfluoropolyether group (i.e., all of the hydrogen atoms onthe carbon atoms are replaced with fluorine atoms). Exemplaryperfluoropolyethers include perfluorinated repeating units representedby at least one of —(C_(d)F_(2d))—, —(C_(d)F_(2d)O)—, —(CF(L′))-,—(CF(L′)O)—, —(CF(L′)C_(d)F_(2d)O)—, —(C_(d)F_(2d)CF(L′)O)—, or—(CF₂CF(L′)O)—. In these repeating units, d is typically an integer from1 to 10. In some embodiments, d is an integer from 1 to 8, 1 to 6, 1 to4, or 1 to 3. The L′ group can be a perfluoroalkyl group optionallyinterrupted by at least one ether linkage or a perfluoroalkoxy group,each of which may be linear, branched, cyclic, or a combination thereof.The L′ group typically has up to 12 (in some embodiments, up to 10, 8,6, 4, 3, 2, or 1) carbon atoms. In some embodiments, the L′ group canhave up to 4 (in some embodiments, up to 3, 2, or 1) oxygen atoms; insome embodiments L′ has no oxygen atoms. In these perfluoropolyetherstructures, different repeating units can be combined in a block orrandom arrangement to form the Rf group.

In some embodiments, Rf is represented by formula R_(f) ^(a)—O—(R_(f)^(b)—O—)_(z′)(R_(f) ^(c))—, wherein R_(f) ^(a) is a perfluoroalkylhaving 1 to 10 (in some embodiments, 1 to 6, 1 to 4, 2 to 4, or 3)carbon atoms; each R_(f) ^(b) is independently a perfluoroalkylenehaving 1 to 4 (i.e., 1, 2, 3, or 4) carbon atoms; R_(f) ^(c) is aperfluoroalkylene having 1 to 6 (in some embodiments, 1 to 4 or 2 to 4)carbon atoms; and z′ is in a range from 2 to 50 (in some embodiments, 2to 25, 2 to 20, 3 to 20, 3 to 15, 5 to 15, 6 to 10, or 6 to 8).Representative R_(f) ^(a) groups include CF₃—, CF₃CF₂—, CF₃CF₂CF₂—,CF₃CF(CF₃)—, CF₃CF(CF₃)CF₂—, CF₃CF₂CF₂CF₂—, CF₃CF₂CF(CF₃)—,CF₃CF₂CF(CF₃)CF₂—, and CF₃CF(CF₃)CF₂CF₂—. In some embodiments, R_(f)^(a) is CF₃CF₂CF₂—. Representative R_(f) ^(b) groups include —CF₂—,—CF(CF₃)—, —CF₂CF₂—, —CF(CF₃)CF₂—, —CF₂CF₂CF₂—, —CF(CF₃)CF₂CF₂—,—CF₂CF₂CF₂CF₂—, and —CF₂C(CF₃)₂—. Representative R_(f) ^(c) groupsinclude —CF₂—, —CF(CF₃)—, —CF₂CF₂—, —CF₂CF₂CF₂—, and —CF(CF₃)CF₂—. Insome embodiments, R_(f) ^(c) is —CF(CF₃)—.

In some embodiments, (R_(f) ^(b)—O—)_(z′) is represented by—[CF₂O]_(i)[CF₂CF₂O]_(j)—, —[CF₂O]_(i)[CF(CF₃)CF₂O]_(j)—,—[CF₂O]_(i)[CF₂CF₂CF₂O]_(j)—, —[CF₂CF₂O]_(i)[CF₂O]_(j)—,—[CF₂CF₂O]_(i)[CF(CF₃)CF₂O]_(j)—, —[CF₂CF₂O]_(i)[CF₂CF₂CF₂O]_(j)—,—[CF₂CF₂CF₂O]_(i)[CF₂CF(CF₃)O]_(j)—, and[CF₂CF₂CF₂O]_(i)[CF(CF₃)CF₂O]_(j)—, wherein i+j is an integer of atleast 3 (in some embodiments, at least 4, 5, or 6).

In some embodiments, Rf is selected from the group consisting ofC₃F₇O(CF(CF₃)CF₂O)_(k)CF(CF₃)—, C₃F₇O(CF₂CF₂CF₂O)_(k)CF₂CF₂—, orCF₃O(C₂F₄O)_(g)CF₂—, wherein k has an average value in a range from 3 to50 (in some embodiments, 3 to 25, 3 to 15, 3 to 10, 4 to 10, or 4 to 7),and wherein g has an average value in a range from 6 to 50 (in someembodiments, 6 to 25, 6 to 15, 6 to 10, 7 to 10, or 8 to 10). In some ofthese embodiments, Rf is C₃F₇O(CF(CF₃)CF₂O)_(k)CF(CF₃)—, wherein k hasan average value in a range from 4 to 7. In some embodiments, Rf isselected from the group consisting of CF₃O(CF₂O)_(x′)(C₂F₄O)_(y′)CF₂—and F(CF₂)₃—O—(C₄F₈O)_(z′)(CF₂)₃—, wherein x′, y′, and z′ eachindependently has an average value in a range from 3 to 50 (in someembodiments, 3 to 25, 3 to 15, 3 to 10, or even 4 to 10).

In some embodiments, Rf is a polyfluoropolyether group that has a weightaverage molecular weight of at least 750 (in some embodiments at least850 or even 1000) grams per mole. In some embodiments, Rf has a weightaverage molecular weight of up to 6000 (in some embodiments, 5000 oreven 4000) grams per mole. In some embodiments, Rf has a weight averagemolecular weight in a range from 750 grams per mole to 5000 grams permole. Weight average molecular weights can be measured, for example, bygel permeation chromatography (i.e., size exclusion chromatography)using techniques known in the art.

Copolymers according to the present disclosure can be prepared, forexample, by polymerizing a mixture of components typically in thepresence of an initiator. By the term “polymerizing” it is meant forminga polymer or oligomer that includes at least one identifiable structuralelement due to each of the components. Typically, preparing thecopolymer includes combining components comprising at least a firstmonomer having an ultraviolet absorbing group and at least a secondmonomer that is a fluorinated monomer.

Suitable first monomers are those that include benzophenone,benzotriazole, triazine, cinnamate, cyanoacrylate, dicyano ethylene,salicylate, oxanilide, or para-aminobenzoate groups. Examples ofsuitable first monomers include2-(cyano-β,β-biphenylacryloyloxy)ethyl-1-methacrylate,2-(α-cyano-β,β-biphenylacryloyloxy)ethyl-2-methacrylamide,N-(4-methacryloylphenol)-N′-(2-ethylphenyl)oxamide, vinyl4-ethyl-α-cyano-β-phenylcinnamate,2-hydroxy-4-(2-hydroxy-3-methacryloyloxypropoxy)benzophenone,2-hydroxy-4-methacryloyloxybenzophenone,2-hydroxy-4-(2-acryloyloxyethoxy)benzophenone,2-hydroxy-4-(4-acryloyloxybutoxy)benzophenone,2,2′-dihydroxy-4-(2-acryloyloxyethoxy)benzophenone,2-hydroxy-4-(2-acryloyloxyethoxy)-4′-(2-hydroxyethoxy)benzophenone,4-(allyloxy)-2-hydroxybenzophenone,2-(2′-hydroxy-3′-methacrylamidomethyl-5′-octylphenyl)benzotriazole,2-(2-hydroxy-5-vinylphenyl)-2-benzotriazole,2-(2H-benzotriazol-2-yl)-4-methyl-6-(2-propenyl)phenol,2-(2′-hydroxy-5′-methacryloyloxyethylphenyl)-2H-benzotriazole,2-(2′-hydroxy-5′-methacryloyloxyethylphenyl)-5-chloro-2H-benzotriazole,2-(2′-hydroxy-5′-methacryloyloxypropylphenyl)-2H-benzotriazole,2-(2′-hydroxy-5′-methacryloyloxypropylphenyl)-5-chloro-2H-benzotriazole,2-(2′-hydroxy-3′-tert-butyl-5′-methacryloyloxyethylphenyl)-2H-benzotriazole,2-(2′-hydroxy-3′-tertbutyl-5′-methacryloyloxyethylphenyl)-5-chloro-2H-benzotriazole,2,4-diphenyl-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2-methylphenyl)-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2-methoxyphenyl)-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2-ethylphenyl)-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2-ethoxyphenyl)-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,2,4-diphenyl-6-[2-hydroxy-4-(2-methacryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2-methylphenyl)-6-[2-hydroxy-4-(2-methacryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2-methoxyphenyl)-6-[2-hydroxy-4-(2-methacryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2-ethylphenyl)-6-[2-hydroxy-4-(2-methacryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2-ethoxyphenyl)-6-[2-hydroxy-4-(2-methacryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2,4-dimethoxyphenyl)-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2,4-diethoxyphenyl)-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,2,4-bis(2,4-diethylphenyl)-6-[2-hydroxy-4-(2-acryloyloxyethoxy)]-1,3,5-triazine,methacrylates of the foregoing acrylates and acrylates of the foregoingmethacrylates. Combinations of these first monomers may be used toprepare the copolymer. In some embodiments, the first monomer includes atriazine, a benzophenone, or a benzotriazole group. In theseembodiments, the first monomer can be any of the monomers including atriazine, benzophenone, or benzotriazole group listed above. In someembodiments, the first monomer includes a triazine group. In theseembodiments, the first monomer can be any of the monomers including atriazine group listed above.

Many of these first monomers can be obtained commercially from a varietyof chemical suppliers. Others can be prepared by treating a UVA havingan available hydroxyl group (e.g., other than a phenolic hydroxyl grouportho to a triazine, benzoyl, or benzotriazole group) with (meth)acrylicacid or an equivalent thereof using conventional esterification methods.The term (meth)acrylic refers to both acrylic and methacrylic. In thecase of a UVA having an available phenol group (e.g., other than aphenolic hydroxyl group ortho to a triazine, benzoyl, or benzotriazolegroup), the phenol group may be treated with ethylene carbonate orethylene oxide to form a hydroxyethyl group that can then be treatedwith (meth)acrylic acid or an equivalent thereof using conventionalesterification methods.

The components that are useful for preparing the fluorinated polymersdisclosed herein include a second monomer, typically a fluorinatedfree-radically polymerizable monomer independently represented byformula Rf-Q-(C_(m)H_(2m))—O—C(O)—C(R¹)═CH₂,Rf—SO₂—N(R³)—(C_(m′)H_(2m′))—O—C(O)—C(R¹)═CH₂, orRf—CO—N(R⁴)—(C_(m′)H_(2m′))—O—C(O)—C(R¹)═CH₂, wherein Rf, R³, R⁴, R¹, m,and m′ are as defined above.

Some compounds of Formula Rf-Q-(C_(m)H_(2m))—O—C(O)—C(R¹)═CH₂, areavailable, for example, from commercial sources (e.g.,3,3,4,4,5,5,6,6,6-nonafluorohexyl acrylate from Daikin Chemical Sales,Osaka, Japan; 3,3,4,4,5,5,6,6,6-nonafluorohexyl 2-methylacrylate fromIndofine Chemical Co., Hillsborough, N.J.;1H,1H,2H,2H-perfluorooctylacrylate from ABCR, Karlsruhe, Germany; and2,2,3,3,4,4,5,5-octafluoropentyl acrylate and methacrylate and3,3,4,4,5,6,6,6-octafluoro-5-(trifluoromethyl)hexyl methacrylate fromSigma-Aldrich, St. Louis, Mo.). Others can be made by known methods(see, e.g., EP1311637 B1, published Apr. 5, 2006, for the preparation of2,2,3,3,4,4,4-heptafluorobutyl 2-methylacrylate). Compounds wherein Q is—SO₂N(R)— can be made according to methods described in, e.g., U.S. Pat.Nos. 2,803,615 (Albrecht et al.) and U.S. Pat. No. 6,664,354 (Savu etal.), the disclosures of which, relating to free-radically polymerizablemonomers and methods of their preparation, are incorporated herein byreference. A perfluoropolyether monomer of formulaRf—(CO)NHCH₂CH₂O(CO)C(R¹)═CH₂ can be prepared by first reactingRf—C(O)—OCH₃, for example, with ethanolamine to preparealcohol-terminated Rf—(CO)NHCH₂CH₂OH, which can then be reacted with(meth)acrylic acid, (meth)acrylic anhydride, or (meth)acryloyl chlorideto prepare the compound of Formula Rf—(CO)NHCH₂CH₂O(CO)C(R¹)═CH₂,wherein R¹ is methyl or hydrogen, respectively. Other amino alcohols(e.g., amino alcohols of formula NRHXOH) can be used in this reactionsequence. In further examples, an ester of formula Rf—C(O)—OCH₃ or acarboxylic acid of formula Rf—C(O)—OH can be reduced using conventionalmethods (e.g., hydride, for example sodium borohydride, reduction) to analcohol of formula Rf—CH₂OH. The alcohol of formula Rf—CH₂OH can then bereacted with methacryloyl chloride, for example, to provide aperfluoropolyether monomer of formula Rf—CH₂O(CO)C(R¹)═CH₂. Examples ofsuitable reactions and reagents are further disclosed, for example, inthe European patent EP 870 778 A1, published Oct. 14, 1998, and U.S.Pat. No. 3,553,179 (Bartlett et al.).

In some embodiments, copolymers according to the present disclosurefurther comprise at least one (e.g., at least 2, 3, 4, 5, 6, 7, 8, 9,10, 15, or at least 20 up 30, 35, 40, 45, 50, 100, or up to 200) thirddivalent unit independently represented by formula:

wherein each R⁶ is independently hydrogen or methyl (in someembodiments, hydrogen, in some embodiments, methyl), and wherein each R⁵is independently alkyl having from 1 to 4 carbon atoms (in someembodiments, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, ortert-butyl). In some embodiments, each R⁵ is independently methyl orethyl. In some embodiments, each R⁵ is methyl. In some of theseembodiments, the copolymer is prepared by including at least onecompound represented by formula R⁵—O—C(O)—C(R⁶)═CH₂ (e.g., methylmethacrylate, ethyl acrylate, propyl acrylate, butyl acrylate) in thecomponents to be polymerized.

In some embodiments, the copolymer according to present disclosure isrepresented by formula:

wherein Z, R, n, X, V, R¹, Rf, Q, m, R⁵, and R⁶ are as defined above inany of their embodiments, x and y are in a range from 1 to 200, and z isin a range from 0 to 200. However, it should be understood that therepresentation of the order of the divalent units is for convenienceonly and not meant to specify that the copolymer is a block copolymer.Random copolymers having first, second, and optionally third divalentunits are also included in the representation.

The polymerization reaction for making the copolymers according to thepresent disclosure can be carried out in the presence of an addedfree-radical initiator. Free radical initiators such as those widelyknown and used in the art may be used to initiate polymerization of thecomponents. Examples of suitable free-radical initiators include azocompounds (e.g., 2,2′-azobisisobutyronitrile (AIBN),2,2′-azobis(2-methylbutyronitrile), or azo-2-cyanovaleric acid),hydroperoxides (e.g., cumene, tert-butyl or tert-amyl hydroperoxide),dialkyl peroxides (e.g., di-tert-butyl or dicumylperoxide), peroxyesters(e.g., tert-butyl perbenzoate or di-tert-butyl peroxyphthalate), anddiacylperoxides (e.g., benzoyl peroxide or lauryl peroxide).

The free-radical initiator may also be a photoinitiator. Examples ofuseful photoinitiators include benzoin ethers (e.g., benzoin methylether or benzoin butyl ether); acetophenone derivatives (e.g.,2,2-dimethoxy-2-phenylacetophenone or 2,2-diethoxyacetophenone);1-hydroxycyclohexyl phenyl ketone; and acylphosphine oxide derivativesand acylphosphonate derivatives (e.g.,bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide,diphenyl-2,4,6-trimethylbenzoylphosphine oxide,isopropoxyphenyl-2,4,6-trimethylbenzoylphosphine oxide, or dimethylpivaloylphosphonate). Many photoinitiators are available, for examples,from BASF under the trade designation “IRGACURE”. The photoinitiator maybe selected so that the wavelength of light required to initiatepolymerization is not absorbed by the ultraviolet absorbing group.

In some embodiments, the polymerization reaction is carried out insolvent. The components may be present in the reaction medium at anysuitable concentration, (e.g., from about 5 percent to about 80 percentby weight based on the total weight of the reaction mixture).Illustrative examples of suitable solvents include aliphatic andalicyclic hydrocarbons (e.g., hexane, heptane, cyclohexane), aromaticsolvents (e.g., benzene, toluene, xylene), ethers (e.g., diethyl ether,glyme, diglyme, and diisopropyl ether), esters (e.g., ethyl acetate andbutyl acetate), alcohols (e.g., ethanol and isopropyl alcohol), ketones(e.g., acetone, methyl ethyl ketone and methyl isobutyl ketone),halogenated solvents (e.g., methylchloroform,1,1,2-trichloro-1,2,2-trifluoroethane, trichloroethylene,trifluorotoluene, and hydrofluoroethers available, for example, from 3MCompany, St. Paul, Minn. under the trade designations “HFE-7100” and“HFE-7200”), and mixtures thereof.

Polymerization can be carried out at any temperature suitable forconducting an organic free-radical reaction. Temperature and solvent fora particular use can be selected by those skilled in the art based onconsiderations such as the solubility of reagents, temperature requiredfor the use of a particular initiator, and desired molecular weight.While it is not practical to enumerate a particular temperature suitablefor all initiators and all solvents, generally suitable temperatures arein a range from about 30° C. to about 200° C. (in some embodiments, fromabout 40° C. to about 100° C., or from about 50° C. to about 80° C.).

Free-radical polymerizations may be carried out in the presence of chaintransfer agents. Typical chain transfer agents that may be used in thepreparation compositions according to the present invention includehydroxyl-substituted mercaptans (e.g., 2-mercaptoethanol,3-mercapto-2-butanol, 3-mercapto-2-propanol, 3-mercapto-1-propanol, and3-mercapto-1,2-propanediol (i.e., thioglycerol)); poly(ethyleneglycol)-substituted mercaptans; carboxy-substituted mercaptans (e.g.,mercaptopropionic acid or mercaptoacetic acid): amino-substitutedmercaptans (e.g., 2-mercaptoethylamine); difunctional mercaptans (e.g.,di(2-mercaptoethyl)sulfide); and aliphatic mercaptans (e.g.,octylmercaptan, dodecylmercaptan, and octadecylmercaptan).

Adjusting, for example, the concentration and activity of the initiator,the concentration of each of the reactive monomers, the temperature, theconcentration of the chain transfer agent, and the solvent usingtechniques known in the art can control the molecular weight of thecopolymer.

The weight ratio of the first divalent units, second divalent units, andthird divalent units, if present, in the copolymer disclosed herein mayvary. For example, the first divalent units may be present in thecopolymer in a range from 5 to 50 (in some embodiments, 10 to 40 or 10to 30) percent, based on the total weight of the copolymer. The seconddivalent units may be present in a range from 5 to 95 percent, based onthe total weight of the copolymer. In some embodiments, the seconddivalent unit is present in the copolymer in an amount of up to 50, 40,30, 25, 20, or 10 percent by weight, based on the total weight of thecopolymer. When the second divalent unit is present in an amount of atleast 50, 60, 75, or 80 percent, it may be useful to use the copolymerin combination with a second copolymer having a lower weight percentageof second divalent units when making a composition according to thepresent disclosure as described below. When present, third divalentunits may be present in a range from 5 to 90, 20 to 90, 50 to 90, or 50to 80 percent by weight, based on the total weight of the copolymer.

Compositions according to the present disclosure include a fluoropolymerand a copolymer according to any of the aforementioned embodiments. Thefluoropolymer is typically a fluorinated thermoplastic obtained bypolymerizing one or more types of fully fluorinated or partiallyfluorinated monomers (e.g., tetrafluoroethylene, vinyl fluoride,vinylidiene fluoride, hexafluoropropylene, pentafluoropropylene,trifluoroethylene, trifluorochloroethylene, and combinations of these inany useful ratio.) Fluoropolymers useful for practicing the presentdisclosure typically have at least some degree of crystallinity. In someembodiments, fluoropolymers useful for practicing the present disclosurehave weight average molecular weights in a range from 30,000 grams permole to 200,000 grams per mole. In some embodiments, the weight averagemolecular weight is at least 40,000 or 50,000 grams per mole up to100,000, 150,000, 160,000, 170,000, 180,000, or up to 190,000 grams permole. Useful fluoropolymers include ethylene-tetrafluoroethylenecopolymers (ETFE), tetrafluoroethylene-hexafluoropropylene copolymers(FEP), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoridecopolymers (THV), polyvinylidene fluoride (PVDF), blends thereof, andblends of these and other fluoropolymers. Another useful fluoropolymeris a PDVF and hexafluoropropylene (HFP) blend in a variety of usefulrations (e.g., in a range from 50:50 to 95:5 PVDF:HFP, such as 90:10).In some embodiments, the compositions according to the presentdisclosure include the fluoropolymer in an amount of at least 50, 60,70, 80, 85, 90, 95, or 96 percent by weight based on the total weight ofthe composition. In some embodiments, the compositions according to thepresent disclosure include the fluoropolymer in an amount greater than95 percent by weight, based on the total weight of the composition. Insome embodiments, the compositions according to the present disclosureinclude the fluoropolymer in an amount of up to 99.5, 99, or 98 percentby weight based on the total weight of the composition.

The composition comprising the fluoropolymer and the copolymer describedabove can also include non-fluorinated materials. For example, thecomposition can include poly(methyl methacrylate) (PMMA) polymer or acopolymer of methyl methacrylate and a C₂-C₈ alkyl acrylate ormethacrylate. The PMMA polymer or copolymer can have a weight averagemolecular weight of at least 50,000 grams per mole, 75,000 grams permole, 100,000 grams per mole, 120,000 grams per mole, 125,000 grams permole, 150,000 grams per mole, 165,000 grams per mole, or 180,000 gramsper mole. The PMMA polymer or copolymer may have a weight averagemolecular weight of up to 500,000 grams per mole, in some embodiments,up to 400,000 grams per mole, and in some embodiments, up to 250,000grams per mole. In some embodiments, a blend of polyvinylidene fluorideand poly(methyl methacrylate) can be useful.

In some embodiments, the composition according to the present disclosureincludes a second copolymer comprising at least one (e.g., at least 2,3, 4, 5, 6, 7, 8, 9, 10, 15, or at least 20 up to 30, 35, 40, 45, 50,100, or up to 200) third divalent units and at least one (e.g., at least2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or at least 20 up to 30, 35, 40, 45, 50,100, or up to 200) first divalent units. The first and third divalentunits may be as described in any of the embodiments described above forthe first and third divalent units in connection with the copolymeraccording to the present disclosure. The second copolymer may be, forexample, a copolymer of an acrylate- or methacrylate-functionalultraviolet absorbing group and methyl methyacrylate. As described inthe Examples, below, if a copolymer including a high weight percentageof the second divalent units results in some non-uniformity in color,haze, or continuity in a film made from the composition, including thesecond copolymer in the composition can unexpectedly provide a filmhaving uniform color, haze, and caliper.

The composition according to the present disclosure typically includes ablend of the fluoropolymer, the copolymer, and any non-fluorinatedpolymers or second copolymers including the first divalent units. By“blend” it is meant that the fluoropolymer and the copolymer accordingto the present disclosure are not located in separate, distinguishabledomains. In other words, the copolymer is typically dispersed throughoutthe composition; it is not isolated as if in a core-shell polymerparticle. In many embodiments, the components of the composition aresurprisingly compatible, and the composition appears homogeneous whenthe components are blended together.

The advantageous compatibility of the copolymer according to the presentdisclosure and the fluoropolymer in the compositions disclosed hereinallows the compositions to be compounded without organic solvent. Forexample, the copolymer and the fluoropolymer can be melt-processed,compounded, mixed, or milled on conventional equipment. Conveniently,uniform masterbatch compositions can be made that include the copolymeraccording to the present disclosure at relatively high concentrations inthe fluoropolymer. The masterbatch compositions can be extruded (e.g.,in a single- or twin-screw extruder) and formed into films. Afterextrusion, the compositions can also be pelletized or granulated. Themasterbatch compositions can then be extrusion compounded withadditional fluoropolymer or non-fluorinated polymer (e.g., PMMA) andformed into films.

Other stabilizers may be added to the compositions according to thepresent disclosure to improve resistance to UV light. Examples of theseinclude hindered amine light stabilizers (HALS) and anti-oxidants. HALSare typically compounds that can scavenge free-radicals, which canresult from photodegradation. Some suitable HALS include atetramethylpiperidine group, in which the nitrogen atoms on thepiperidine may be unsubstituted or substituted by alkyl or acyl.Suitable HALS include decanedioic acid,bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester,bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate,8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro(4,5)-decane-2,5-dione,bis(2,2,6,6-tetramethyl-4-hydroxypiperidine succinate), andbis(N-methyl-2,2,6,6-tetramethyl-4-piperidyl)secacate. Suitable HALSinclude those available, for example, from BASF, Florham Park, N.J.,under the trade designations “CHIMASSORB”. Exemplary anti-oxidantsinclude those obtained under the trade designations “IRGAFOS 126”,“IRGANOX 1010” and “ULTRANOX 626”, also available from BASF. Thesestabilizers, if present, can be included in the compositions accordingto the present disclosure in any effective amount, typically up to 5, 2,to 1 percent by weight based on the total weight of the composition andtypically at least 0.1, 0.2, or 0.3 percent by weight. Calcite may alsobe a useful additive in some compositions, for example, to protectagainst corrosion of processing equipment not made of corrosionresistant steel.

In some embodiments of the composition according to the presentdisclosure, the composition can be included in one or more layers of amultilayer film. The multilayer film is any film having more than onelayer, typically in the thickness direction of the film. For example,the multilayer film may have at least two or three layers up to 10, 15,or 20 layers. In some embodiments, the composition may be included in amirror film, which may have a layer (or layers) of the compositionaccording to the present disclosure and a metal layer. In someembodiments, the composition can be included in a multilayer opticalfilm (that is, having an optical layer stack), for example, such asthose described in U.S. Pat. App. Pub. Nos. 2009/0283144 (Hebrink etal.) and 2012/0011850 (Hebrink et al.). Multi-layer optical films mayhave, for example, at least 100, 250, 500, or even at least 1000 opticallayers. Such multi-layer optical films can be useful as ultravioletlight-reflective mirrors, visible light-reflective mirrors, infraredlight-reflective mirrors, or any combination of these (e.g., broadbandreflective mirrors). In some of these embodiments, the multilayeroptical film reflects at least a major portion of the average lightacross the range of wavelengths that corresponds with the absorptionbandwidth of a selected photovoltaic cell and does not reflect a majorportion of the light that is outside the absorption bandwidth of thephotovoltaic cell. In other embodiments, the multilayer optical film maybe combined with a metal layer to provide a broadband reflector. In someembodiments, the composition according to the present disclosure may beuseful, for example, as a retroreflective sheet.

In view of the advantageous compatibility of the copolymer according tothe present disclosure and the fluoropolymer in the compositionsdisclosed herein, the present disclosure provides a method of making acomposition and a method of making a film. The method of making acomposition includes blending the copolymer according to the presentdisclosure with a fluoropolymer to make the composition. The method ofmaking a film includes providing a composition according to the presentdisclosure, which includes at least the fluoropolymer and the copolymer,and extruding the composition into a film. The method may also includeblending the composition with additional fluoropolymer ornon-fluorinated polymer (e.g., if the composition is a masterbatchcomposition) before extruding the composition into a film.

In some embodiments of the composition or methods of making thecomposition or the film, the composition is essentially free of volatileorganic solvent. Volatile organic solvents are typically those have aboiling point of up to 150° C. at atmospheric pressure. Examples ofthese include esters, ketones, and toluene. “Essentially free ofvolatile organic solvent” can mean that volatile organic solvent may bepresent (e.g., from a previous synthetic step or in a commerciallyavailable monomer) in an amount of up to 2.5 (in some embodiments, up to2, 1, 0.5, 0.1, 0.05, or 0.01) percent by weight, based on the totalweight of the composition. Advantageously, compositions disclosed hereinand their films can be made without the expensive manufacturing step ofremoving organic solvent.

The composition according to the present disclosure can include thecopolymer according to the present disclosure in a range of usefulamounts. For example, the copolymer may be present in the composition atup to about 20 percent by weight, based on the total weight of thecomposition. In some embodiments, the copolymer and the second copolymerare present in the composition in an amount up to 20 percent combinedweight, based on the total weight of the composition. For a masterbatch,useful amounts of the copolymer or the copolymer combined with thesecond polymer may be in a range from 2 to 20, 3 to 15, or 4 to 10percent by weight, based on the total weight of the composition. For afinal film article, for example, useful amounts of the copolymer or thecopolymer combined with the second polymer may be in a range from 0.5 to10, 0.5 to 5, or 1 to 5 percent by weight, based on the total weight ofthe composition. As shown in the Examples, below, compositions withultraviolet light-absorbing oligomers in this range are quite effectiveat absorbing ultraviolet light, and the ultraviolet light protection ismaintained even after weathering or exposure to heat and humidity. Thisis unexpected in view of JP2001/19895, published Jan. 23, 2001, whichsuggests that polymeric ultraviolet light absorbers are most useful incompositions at 30 to 60 parts per hundred.

The advantageous compatibility of the copolymer according to the presentdisclosure and the fluoropolymer in the compositions disclosed herein,which allows the compositions to be extrusion compounded, for example,is not found in other many compositions including UVAs andfluoropolymers.

For example, while a compound represented by formula

Wherein R^(A) is C₁₋₂₀ alkyl or aryl and R^(B), R^(C), R^(D), and R^(E)are hydrogen, C₁₋₅ alkyl, hydroxyl, or aryl are said to be useful UVAsin polymer blends (see, e.g., JP2001/001478, published, Jan. 9, 2001),Comparative Examples 1 and 2, below, show that2-(4,6-diphenyl-1,3,5-triazin-2-yl-)-5-((hexyl)oxyphenol and2-[4-[(2-hydroxy-3-(2′-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazinewhen mixed with PVDF provided more haze, less clarity, and less visibleand infrared light transmission than the copolymers according to thepresent disclosure. Also, when a triazine UV absorber obtained fromBASF, Florham Park, N.J., under the trade designation “TINUVIN 1600” wasextrusion compounded with PVDF, the resulting strands were very hazy anddifficult to pelletize.

Furthermore, while incorporating acryloyl or methacryloyl functional2-hydroxybenzophenones or 2-hydroxyphenyl-2H-benzotriazoles into highmolecular weight PMMA has been proposed, low weathering resistance wasobserved in comparison to non-covalently attached UVAs (see, U.S. Pat.Appl. Pub. No. 2010/0189983 (Numrich et al.). In contrast, thecopolymers according to the present disclosure have excellent resistanceto weathering, as demonstrated by high retention of percent transmissionof visible light and low transmission of ultraviolet light afterweathering according to the method described in the Examples, below.

In some embodiments, compositions according to the present disclosureare transmissive to both visible and infrared light. The term“transmissive to visible and infrared light” as used herein can meanhaving an average transmission over the visible and infrared portion ofthe spectrum of at least about 75% (in some embodiments at least about80, 85, or 90, 92, 95, 97, or 98%) measured along the normal axis. Insome embodiments, the composition has an average transmission over arange of 400 nm to 1400 nm of at least about 75% (in some embodiments atleast about 80, 85, 90, 92, 95, 97, or 98%).

Compositions according to the present disclosure may be useful for avariety of outdoor applications. For example, the compositions accordingto the present disclosure may be useful, for example, for top layers oftraffic or other signs, automotive exteriors, roofing materials or otherarchitectural films, or window films.

Compositions according to the present disclosure are useful, forexample, for encapsulating solar devices. In some embodiments, thecomposition (e.g., in the form of a film) is disposed on, above, oraround a photovoltaic cell. Accordingly, the present disclosure providesa photovoltaic device including the composition disclosed herein inwhich the composition (e.g., in the form of a film) is used as a topsheet for the photovoltaic device. Photovoltaic devices includephotovoltaic cells that have been developed with a variety of materialseach having a unique absorption spectrum that converts solar energy intoelectricity. Each type of semiconductor material has a characteristicband gap energy which causes it to absorb light most efficiently atcertain wavelengths of light, or more precisely, to absorbelectromagnetic radiation over a portion of the solar spectrum. Thecompositions according to the present disclosure typically do notinterfere with absorption of visible and infrared light, for example, byphotovoltaic cells. In some embodiments, the composition has an averagetransmission over a range wavelengths of light that are useful to aphotovoltaic cell of at least about 75% (in some embodiments at leastabout 80, 85, 90, 92, 95, 97, or 98%). Examples of materials used tomake solar cells and their solar light absorption band-edge wavelengthsinclude: crystalline silicon single junction (about 400 nm to about 1150nm), amorphous silicon single junction (about 300 nm to about 720 nm),ribbon silicon (about 350 nm to about 1150 nm), CIS (Copper IndiumSelenide) (about 400 nm to about 1300 nm), CIGS (Copper Indium Galliumdi-Selenide) (about 350 nm to about 1100 nm), CdTe (about 400 nm toabout 895 nm), GaAs multi-junction (about 350 nm to about 1750 nm). Theshorter wavelength left absorption band edge of these semiconductormaterials is typically between 300 nm and 400 nm. Organic photovoltaiccells may also be useful. One skilled in the art understands that newmaterials are being developed for more efficient solar cells havingtheir own unique longer wavelength absorption band-edge. In someembodiments, the photovoltaic device including the composition accordingto the present disclosure includes a CIGS cell. In some embodiments, thephotovoltaic device to which the assembly is applied comprises aflexible film substrate.

A composition according to the present disclosure (e.g., in the form ofa film) can be used as a substrate for a barrier stack (see, e.g., U.S.Pat. Appl. Pub. No. 2012/0227809 (Bharti et al.) or can be attached to abarrier stack using an optically clear adhesive such as a pressuresensitive adhesive (PSA) (see, e.g., U.S. Pat. Appl. Pub. No.2012/0003451 (Weigel et al.). Examples of PSAs include acrylates,silicones, polyisobutylenes, ureas, and combinations thereof Some usefulcommercially available PSAs include UV curable PSAs such as thoseavailable from Adhesive Research, Inc., Glen Rock, Pa., under the tradedesignations “ARclear 90453” and “ARclear 90537” and acrylic opticallyclear PSAs available, for example, from 3M Company, St. Paul, Minn.,under the trade designations “OPTICALLY CLEAR LAMINATING ADHESIVE 8171”,“OPTICALLY CLEAR LAMINATING ADHESIVE 8172”, and “OPTICALLY CLEARLAMINATING ADHESIVE 8172P”. In some embodiments, the top sheet andbarrier film assembly is attached to the photovoltaic cell with anencapsulant. Although other encapsulants may be useful, in someembodiments, the encapsulant is ethylene vinylacetate.

Some Embodiments of the Disclosure

In a first embodiment, the present disclosure provides a copolymercomprising: a first divalent unit comprising a pendent ultravioletabsorbing group; and a second divalent unit represented by formula:

wherein

-   -   Rf represents a fluoroalkyl group having from 1 to 6 carbon        atoms optionally interrupted by one —O— group, or Rf represents        a polyfluoropolyether group;    -   R¹ is hydrogen or methyl;    -   Q is a bond, —SO₂—N(R)—, or —C(O)—N(R)—, wherein R is alkyl        having from 1 to 4 carbon atoms or hydrogen; and

m is an integer from 0 to 11,

wherein the copolymer is a thermoplastic copolymer.

In a second embodiment, the present disclosure provides the copolymer ofthe first embodiment, wherein the pendent ultraviolet absorbing groupcomprises a triazine, a benzophenone, or a benzotriazole.

In a third embodiment, the present disclosure provides the copolymer ofthe first or second embodiment, wherein the first divalent unit isrepresented by formula:

wherein

-   -   R¹ is hydrogen or methyl;    -   V is O or NH;    -   X is alkylene or alkyleneoxy group having from 1 to 10 carbon        atoms and optionally interrupted by one or more —O— groups and        optionally substituted by a hydroxyl group;    -   R is alkyl having from one to four carbon atoms;    -   n is 0 or 1; and    -   Z is a benzoyl group, a 4,6-bisphenyl[1,3,5]triazin-2-yl group,        or a 2H-benzotriazol-2-yl group, wherein the benzoyl group,        4,6-bisphenyl[1,3,5]triazin-2yl group, and 2H-benzotriazol2-yl        group are optionally substituted by one or more alkyl, aryl,        alkoxy, hydroxyl, or halogen substituents, or a combination of        these substituents.

In a fourth embodiment, the present disclosure provides the copolymer ofany one of the first to third embodiments, wherein the pendentultraviolet absorbing group comprises a triazine.

In a fifth embodiment, the present disclosure provides the copolymer ofany one of the first to fourth embodiments, wherein Rf represents aperfluoroalkyl group having up to 4 carbon atoms.

In a sixth embodiment, the present disclosure provides the copolymer ofany one of the first to fifth embodiments, further comprising a thirddivalent unit represented by formula:

wherein R⁶ is hydrogen or methyl; and R⁵ is alkyl having from 1 to 4carbon atoms.

In a seventh embodiment, the present disclosure provides the copolymerany one of the first to sixth embodiments, wherein the second divalentunit is present in the copolymer in an amount of up to 50 percent byweight, based on the total weight of the copolymer.

In an eighth embodiment, the present disclosure provides the copolymerof any one of the first to seventh embodiments, wherein the copolymer isan oligomer with a number average molecular weight of up to 50,000 gramsper mole.

In a ninth embodiment, the present disclosure provides the copolymer ofthe eighth embodiment, wherein the oligomer has a number averagemolecular weight greater than 5000 grams per mole.

In a tenth embodiment, the present disclosure provides the copolymer ofthe eighth or ninth embodiment, wherein the oligomer has a numberaverage molecular weight of less than 20000 grams per mole.

In an eleventh embodiment, the present disclosure provides a compositioncomprising a fluoropolymer and the copolymer of any one of the first totenth embodiments.

In a twelfth embodiment, the present disclosure provides the compositionof the eleventh embodiment, further comprising poly(methylmethacrylate).

In a thirteenth embodiment, the present disclosure provides thecomposition of the eleventh or twelfth embodiment, wherein thefluoropolymer is present in the composition in an amount of at least 50percent by weight, based on the total weight of the composition.

In a fourteenth embodiment, the present disclosure provides thecomposition of any one of the eleventh to thirteenth embodiments,wherein the copolymer is present in the composition in an amount up to10 percent by weight, based on the total weight of the composition. Insome of these embodiments, the copolymer is present in the compositionin an amount ranging from 0.5 percent to 5 percent by weight, based onthe total weight of the composition.

In a fifteenth embodiment, the present disclosure provides thecomposition of any one of the eleventh to fourteenth embodiments,further comprising a second copolymer comprising the first divalent unitand at least one of the second or third divalent units.

In a sixteenth embodiment, the present disclosure provides thecomposition of the fifteenth embodiment, wherein the second copolymer isa copolymer of methyl methacrylate and an acrylate- ormethacrylate-functional ultraviolet absorbing group.

In a seventeenth embodiment, the present disclosure provides thecomposition of the fifteenth or sixteenth embodiment, wherein thecopolymer and the second copolymer are present in the composition in anamount up to 10 percent combined weight, based on the total weight ofthe composition.

In an eighteenth embodiment, the present disclosure provides thecomposition of any one of the eleventh to seventeenth embodiments,wherein the composition is essentially free of volatile organic solvent.

In a nineteenth embodiment, the present disclosure provides thecomposition of any one of the eleventh to eighteenth embodiments,wherein the fluoropolymer is selected from the group consisting ofethylene-tetrafluoroethylene copolymer, atetrafluoroethylene-hexafluoropropylene copolymer, atetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer,or polyvinylidene fluoride.

In a twentieth embodiment, the present disclosure provides thecomposition of any one of the eleventh to nineteenth embodiments,wherein the composition is in the form of a film.

In a twenty-first embodiment, the present disclosure provides thecomposition of the twentieth embodiment, wherein the film is amultilayer film.

In a twenty-second embodiment, the present disclosure provides thecomposition of the twenty-first embodiment, wherein the film is amultilayer optical film.

In a twenty-third embodiment, the present disclosure provides aphotovoltaic device comprising the composition of any one of theeleventh to twenty-second embodiments.

In a twenty-fourth embodiment, the present disclosure provides a methodof making a film, the method comprising providing the composition of anyone of the eleventh to twenty-second embodiments and extruding thecomposition into the film.

In a twenty-fifth embodiment, the present disclosure provides a methodof making a composition, the method comprising blending the copolymer ofany one of the first to tenth embodiments with a fluoropolymer to makethe composition.

Embodiments of the methods disclosed herein are further illustrated bythe following examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this invention.

EXAMPLES Preparative Example 12-{4-[4,6-Bis-(2,4-dimethyl-phenyl)-[1,3,5]triazin-2-yl]-3-hydroxy-phenoxy}-ethylacrylate ester

Part A

A three liter 3-neck round bottom flask was equipped with a temperatureprobe, condenser and mechanical stirrer. The flask was charged with 500grams (1.26 moles) of2,4-di-(2,4-dimethylphenyl)-6-(2,4-dihydroxyphenyl)-triazine, 124 grams(1.4 moles) of ethylene carbonate, 18 grams (0.085 moles)tetraethylammonium bromide and 475 grams of dimethyl formamide. Thebatch was heated to 150° C. and maintained at that temperature for fivehours. The evolution of CO₂ from the batch was observed. After fivehours, 15 grams additional ethylene carbonate and 2 grams additionaltetraethylammonium bromide were added. The batch was heated at 150° C.for three hours, and then 15 grams additional ethylene carbonate and 2grams additional tetraethylammonium bromide were added. The batch washeated at 150° C. for three more hours, after which time no morestarting material was observed by thin layer chromatography.

The batch was allowed to cool to 80° C., and 1360 grams of isopropanol(IPA) was added with good agitation. The mixture was cooled to roomtemperature, and the solid product was collected by filtration onto aBuchner funnel The solid product was taken up into 1000 grams each ofwater and IPA, stirred well, and collected by filtration onto a Buchnerfunnel The product was air-dried to give 540 grams (96%) of an off-whitesolid product,2-[4,6-bis-(2,4-dimethylphenyl)-[1,3,5]triazin-2-yl]-5-(2-hydroxyethoxy)phenol,mp=172° C.-173° C. The product was used without further purification.

Part B

A two liter 3-neck round bottom flask was equipped with a temperatureprobe, Dean-Stark trap with condenser, and mechanical stirrer. The flaskwas charged with 170 grams (0.385 moles) of2-[4,6-bis-(2,4-dimethylphenyl)-[1,3,5]triazin-2-yl]-5-(2-hydroxyethoxy)phenol,prepared in Part A, 780 grams of toluene, 0.24 grams of 4-methoxyphenol(MEHQ) inhibitor, 0.38 grams of phenothiazine inhibitor, 8.5 grams ofp-toluene sulfonic acid, and 30.5 grams (0.42 moles) of acrylic acid.The batch was heated with medium agitation at reflux (about 115° C.) forsix hours, and the azeotroped water can collected in the Dean-Starktrap. After five hours, five grams additional acrylic acid was added,and the batch was heated for three more hours. Analysis by thin layerchromatography showed the batch had no residual starting material.

The batch was allowed to cool to 80° C., and a pre-mix of 25 gramssodium carbonate in 300 grams water was added. The reaction mixture wascooled to about 10° C. with an ice bath, and the precipitated productwas collected by filtration on a Buchner funnel The solid was taken backup in a mixture of 800 grams water and 200 grams IPA, and the mixturewas stirred well and filtered. The product was air-dried to give 182grams (96%) of the off-white solid product,2-{4-[4,6-bis-(2,4-dimethyl-phenyl)-[1,3,5]triazin-2-yl]-3-hydroxyphenoxy}ethylacrylate ester, mp=126° C.-128° C.

Preparative Example 2 2-(4-Benzoyl-3-hydroxyphenoxy)ethyl acrylate ester

Part A

A five liter 3-neck round bottom flask was equipped with a temperatureprobe, condenser, and mechanical stirrer. The flask was charged with 500grams (2.33 moles) of 2,4-dihydroxybenzophenone, 216 grams (2.45 moles)of ethylene carbonate, and 25 grams (0.12 moles) tetraethylammoniumbromide. The batch was heated to 140° C. and maintained at thattemperature for twenty-four hours. The evolution of CO₂ from the batchwas observed. Analysis by thin layer chromatography showed the batch hadno residual starting material.

The batch was allowed to cool to 80° C., and 1200 grams of isopropanolwas added with good agitation. The batch temperature was held at about60° C., and 2500 grams of water was added while maintaining the batchtemperature at about 60° C. The batch was cooled to room temperaturewith slow agitation, and the product was collected by filtration onto aBuchner funnel The solid product was taken back up into 1000 grams ofwater and 200 grams of IPA, stirred well, and collected by filtrationonto a Buchner funnel The product was air-dried to give 545 grams (90%)of an off-white solid product, 2-hydroxy-4-(2-hydroxyethyl)benzophenone,mp=88° C.-89° C. The product was used without further purification.

Part B

A two liter 3-neck round bottom flask was equipped with a temperatureprobe, Dean-Stark trap with condenser, and mechanical stirrer. The flaskwas charged with 200 grams (0.77 moles) of2-hydroxy-4-(2-hydroxyethyl)benzophenone, prepared in Part A, 850 gramstoluene, 0.48 grams MEHQ inhibitor, 0.77 grams phenothiazine inhibitor,17 grams p-toluene sulfonic acid, and 61.4 grams (0.85 moles) of acrylicacid. The batch was heated with medium agitation at reflux (about 115°C.) for six hours, and the azeotroped water was collected in theDean-Stark trap. After five hours, five grams additional acrylic acidwas added, and the batch was heated for three more hours. Analysis bythin layer chromatography showed the batch had no residual startingmaterial.

The batch was cooled to 80° C., and a pre-mix of 25 grams sodiumcarbonate in 300 grams water was added. The batch was phase split, andthe lower aqueous layer was removed. The organic layer was washed with amixture of 25 grams sodium chloride in 300 grams water. The solvent wasstripped using a rotary evaporator. The residual brown oil product wastaken up in 230 grams of IPA, and heated to about 60° C. to make asolution. The mixture was agitated gently and cooled to −10° C. tocrystallize the off-white solid product. The product was air-dried togive 217 grams (90%) of the off-white solid product,2-(4-benzoyl-3-hydroxyphenoxy)ethyl acrylate ester, mp=126° C.-128° C.

Preparative Example 3 Heptafluorobutyl Methacrylate

Heptafluorobutanol (1890 grams, 9.45 moles), 30 grams of 95% sulfuricacid, 1.8 grams of phenothiazine, 1.5 grams of MEHQ were placed in a 3liter flask that was fitted with an overhead stirrer, thermocouple, anda addition funnel The reaction was heated to 55° C., and at that timethe addition of methacrylic anhydride (1527 grams, 9.91 moles) wasbegun. The batch exothermed to 65° C., and the addition was adjusted tokeep the reaction temperature at 65° C. At this time the set point ofthe controller was raised to 65° C. The addition of methacrylicanhydride was completed in 2.5 hours. The reaction mixture was thenheated at 65° C. for 3 hours and then allowed to cool to roomtemperature. Analysis by gas chromatography (GC) indicated the materialto be 0.4% unreacted heptafluorobutanol, 0.9% heptafluorobutyl acetate,63.6 desired heptafluorobutyl methacrylate, 30.6% methacrylic acid, and0.4 unreacted methacrylic anhydride.

1800 grams of water was added, and the batch was stirred for 30 minutes.The pH was measured at less than 2; analysis by GC showed the materialto be 1.0% heptafluorobutyl acetate, 70.9 desired heptafluorobutylmethacrylate, 22.9% methacrylic acid, and 1.4% unreacted methacrylicanhydride. The black water phase was split off from the translucentolive/brown fluorochemical phase; 3006 grams of fluorochemical phase wasobtained.

Another 1800 grams of water was added to the fluorochemical phase, andthe batch was stirred for 30 minutes. The pH was measured at less than2; analysis by GC showed the material to be 1.1% heptafluorobutylacetate, 74.7% desired heptafluorobutyl methacrylate, 19% methacrylicacid, and 1.4% unreacted methacrylic anhydride. The light green waterphase was split off from the translucent green flluorochemical phase;2840 grams of fluorochemical phase was obtained.

The batch was allowed to split, and the translucent amethystfluorochemical bottom phase was split off and saved. The fluorochemicalphase was then stirred for 30 minutes with a mixture of 285 grams ofpotassium hydroxide and 1800 grams of water. The bottom raspberrycolored fluorochemical phase was split off to give 2537 grams of thecrude product; analysis by GC showed the material to be 1.3%heptafluorobutyl acetate, 88.3% desired heptafluorobutyl methacrylate,6.7% methacrylic acid, and 1.4 unreacted methacrylic anhydride.

For the next wash the batch was added to 85 g of potassium carbonatedissolved in 1800 g of water and stirred for 30 min with the previouslywashed FC product. GC showed the material to be 1.3% heptafluorobutylacetate and 94.4% desired heptafluorobutyl methacrylate. Methacrylicacid and unreacted methacrylic anhydride were not detected. The pH ofthe water layer was measured at 10-11. The product weighed 2275 grams.This material was washed again with 1800 grams of water for 30-minutes.The pH of the water layer was measured at 7-8. A total of 2235 grams ofthe product was isolated after separation of the water layer.

The crude heptafluorobutyl methacrylate was added to a 3 liter flaskfitted with a distillation head and a thermocouple. More inhibitor (3grams of phenothiazine and 0.7 gram of MEHQ) were added to thedistillation pot. The acrylate was distilled to give 156 of precutdistilling at 142 mm Hg at a head temperature of 80° C.-86° C. (88%desired methacrylate). The desired material distilled at 86° C. -° C. at131 mm Hg; a total of 1934 grams of heptafluorobutyl methacrylate wereobtained.

Molecular Weight Determination

In the following copolymer examples, the molecular weight was determinedby comparison to linear polystyrene polymer standards using gelpermeation chromatography (GPC). The GPC measurements were carried outon a Waters Alliance 2695 system (obtained from Waters Corporation,Milford, Mass.) using four 300 millimeter (mm) by 7 8 mm linear columnsof 5 micrometer styrene divinylbenzene copolymer particles (obtainedfrom Polymer Laboratories, Shropshire, UK, under the trade designation“PLGEL”) with pore sizes of 10,000, 1000, 500, and 100 angstroms. Arefractive index detector from Waters Corporation (model 410) was usedat 40° C. A 50-milligram (mg) sample of copolymer in ethyl acetate wasdiluted with 10 milliliters (mL) of tetrahydrofuran (inhibited with 250ppm of BHT) and filtered through a 0.45 micrometer syringe filter. Asample volume of 100 microliters was injected onto the column, and thecolumn temperature was 40° C. A flow rate of 1 mL/minute was used, andthe mobile phase was tetrahydrofuran. Molecular weight calibration wasperformed using narrow dispersity polystyrene standards with peakaverage molecular weights ranging from 3.8×10⁵ grams per mole to 580grams per mole. Calibration and molecular weight distributioncalculations were performed using suitable GPC software using a thirdorder polynomial fit for the molecular weight calibration curve. Eachreported result is an average of duplicate injections.

Glass Transition Temperature

For the following copolymer examples, the glass transition temperatureswere measured by Differential Scanning Calorimetry (DSC) using a Q2000Differential Scanning Calorimeter obtained from TA Instruments, NewCastle, Del. Glass transition temperature was determined using ModulatedDSC with a modulation amplitude of ±1° C. per minute and a ramp rate of3° C. per minute.

Copolymer Example 1 Random Copolymer of 10% by Weight PreparativeExample 3, 70% by Weight Methyl Methacrylate, and 20% by WeightPreparative Example 1

A five-liter flask was equipped with an overhead stirrer, athermocouple, and a reflux condenser. With nitrogen flowing though theopening used for charging (from adapter at top of reflux condenser), 50grams Preparative Example 3, 350 grams of methyl methacrylate (obtainedfrom Alfa Aesar, Ward Hill, Mass.), 100 grams of Preparative Example 1,and 2500 grams of ethyl acetate were added. After charging, the batchwas kept under sight positive nitrogen pressure in order to excludeoxygen from the batch. The set point on the controller for thethermocouple (obtained from J-Kem, St. Louis, Mo.) was raised to 70° C.,and 14 grams of 2,2′-azobis(2-methylbutyronitrile) (obtained from E.I.du Pont de Nemours and Company, Wilmington, Del., under the tradedesignation “VAZO 67”) were added. The batch was observed for 15minutes. The set point was raised to 74° C., and the timer was set for18 hours. The batch was allowed to come to room temperature. The batchhad olive-colored solid floating in it and was filtered through grade 40filter paper obtained from Whatman, Kent, UK, to give a clear yellowsolution.

The solution was poured out into four aluminum trays and dried at roomtemperature overnight, then at 100° C. for 4 hours, and then one hour at120° C. A total of 514 grams of solid was isolated. The trays wereallowed to cool to room temperature to a hard material, which wasprocessed into a powder.

The procedure was repeated five times. The molecular weight of thereaction mixture, before drying, was determined by gel permeationchromatography using the method described above. The results for thefive runs are shown in Table 1, below.

TABLE 1 Run Mw Mn Mz Mw/Mn 1 1.376E+04 7.021E+03 2.027E+04 1.96 21.373E+04 7.012E+03 2.011E+04 1.96 3 1.407E+04 7.887E+03 2.043E+04 1.784 1.439E+04 8.051E+03 2.107E+04 1.79 5 1.494E+04 8.241E+03 2.182E+041.81

Copolymer Example 2 Random Copolymer of 80% by Weight PreparativeExample 3 and 20% by Weight Preparative Example 1

Copolymer Example 2 was prepared using the method of Co-polymer Example1 except using 400 grams Preparative Example 3, 100 grams of PreparativeExample 1, and 14 grams of a 50/50 mixture of mineral spirits/tert-butylperoxy-2-ethylhexanoate (obtained from Atofina, Philadelphia, Pa., underthe trade designation “LUPEROX 26M50”) instead of2,2′-azobis(2-methylbutyronitrile). The glass transition temperature wasmeasured using DSC using the method described above and found to be 38°C. The procedure was repeated five times. The molecular weight of thereaction mixture, before drying, was determined by gel permeationchromatography using the method described above. Two samples wereanalyzed for each run, and the results are shown in Table 2, below.

TABLE 2 Mw Mn Mz Sample (Daltons) (Daltons) (Daltons) Mw/Mn Run 1-Sample1 21930 12392 33153 1.77 Run 1-Sample 2 21389 13593 31719 1.57 Run2-Sample 1 20364 12548 30056 1.62 Run 2-Sample 2 20352 12681 29911 1.60Run 3-Sample 1 20950 13290 30616 1.58 Run 3-Sample 2 21056 13083 310891.61 Run 4-Sample 1 20286 12682 29802 1.60 Run 4-Sample 2 20255 1266829648 1.60 Run 5-Sample 1 26914 16547 39830 1.63 Run 5-Sample 2 2680016681 39449 1.61

Copolymer Example 3 Random Copolymer of 80% by Weight PreparativeExample 3 and 20% by Weight Preparative Example 2

Copolymer Example 3 was prepared using the method of Copolymer Example 2except using 100 grams Preparative Example 2 instead of 100 grams ofPreparative Example 1. The batch was clear at the end of the reaction,so no filtration was performed. Two glass transition temperatures wasobserved at 62.1° C. and 83° C. using DSC according to the methoddescribed above. The molecular weight of the reaction mixture wasdetermined by GPC using the method described above. The analysis wasdone for five different runs as described in Copolymer Example 1, andthe results are shown in Table 3, below.

TABLE 3 Run Mw (Daltons) Mn (Daltons) Mz (Daltons) Mw/Mn 1 27199 1630940430 1.67 2 26860 15966 40328 1.68 3 25926 15062 38899 1.72 4 2739716493 40929 1.66 5 27266 16179 40859 1.69

Copolymer Example 4 Random Copolymer of 10% by Weight PreparativeExample 3, 70% by Weight Methyl Methacrylate, and 20% by Weight2-{2-Hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl}-2H-benzotriazole

Copolymer Example 4 was prepared using the method of Copolymer Example 1except using 100 grams2-{2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl}-2H-benzotriazole(obtained from TCI America, Portand, Oreg.) instead of 100 grams ofPreparative Example 1. The batch was clear at the end of the reaction,so no filtration was performed. A glass transition temperature wasmeasured at 56.0° C. by DSC using the test method described above. Usingthe GPC method described above, the weight average molecular weight wasfound to be 20420 Daltons, the number average molecular weight was foundto be 11880 Daltons, and the Z average molecular weight was found to be31080 Daltons. A polydispersity of 1.73 was calculated. The GPC analysiswas carried out on one sample.

Copolymer Example 5 Random Copolymer of 10% by WeightC₃F₇O(C₃F₆O)_(5.9)CFCF₂C(O)NHCH₂CH₂OC(O)C(CH₃)═CH₂, 70% by Weight MethylMethacrylate, and 20% by Weight Preparative Example 1

Copolymer Example 5 was prepared using the method of Copolymer Example 1except using 22 grams ofC₃F₇O(C₃F₆O)_(5.9)CFCF₂C(O)NHCH₂CH₂OC(O)C(CH₃)═CH₂ instead ofPreparative Example 3, 154 grams of methyl methacrylate, 44 grams ofPreparative Example 1, 1100 grams of ethyl acetate, and 6.1 grams of2,2′-azobis(2-methylbutyronitrile).C₃F₇O(C₃F₆O)_(k)CFCF₂C(O)NHCH₂CH₂OC(O)CH═CH₂ was prepared in two steps.First C₃F₇O(C₃F₆O)_(5.9)CFCF₂C(O)NHCH₂CH₂OH with an average molecularweight of 1313 grams per mole was prepared as described in U.S. Pat. No.6,923,921 (Flynn et al.) The methacrylate was prepared as in U S. Pat.No. 7,101,618 (Coggio et al.) Preparation Example 1 except thatmethacryloyl chloride was used instead of acryloyl chloride. The batchwas clear at the end of the reaction, so no filtration was performed.The glass transition temperature was measured using DSC using the methoddescribed above and found to be 87.2° C. Using the GPC method describedabove, the weight average molecular weight was found to be 19910Daltons, the number average molecular weight was found to be 12750Daltons, and the Z average molecular weight was found to be 28700Daltons. A polydispersity of 1.56 was calculated. The GPC analysis wascarried out on one sample.

Copolymer 6 Random Copolymer of 80% by Weight Methyl Methacrylate and20% Preparative Example 2

Copolymer Example 6 was prepared using the method of Copolymer Example 1except using no Preparative Example 3, using 400 grams of methylmethacrylate, and using 100 grams of Preparative Example 2 instead ofPreparation Example 1. The batch was clear at the end of the reaction,so no filtration was performed. The glass transition temperature wasmeasured using DSC using the method described above and found to be71.5° C. The molecular weight of the reaction mixture was determined byGPC using the method described above. The reaction was run three times,and 2 or 3 samples were analyzed from each run. The results are shown inTable 4, below.

TABLE 4 Mw Mn Mz Sample (Daltons) (Daltons) (Daltons) Mw/Mn Run 1-Sample1 27756 18533 38428 1.50 Run 1-Sample 2 26654 17737 36863 1.50 Run1-Sample 3 26573 17687 36828 1.50 Run 2-Sample 1 26683 17681 37032 1.51Run 2-Sample 2 26685 17546 37068 1.52 Run 3-Sample 1 27551 18376 381021.50 Run 3-Sample 2 27423 18184 37962 1.51

Haze and Clarity Measurements

The haze and clarity of the film examples below were measured using aHaze-Gard Plus (BYK-Gardner USA, Columbia, Md.).

Accelerated Ultraviolet Light Exposure

Films were exposed in a weathering device according to a high-irradianceversion of ASTM G155 Cycle 1 run at slightly higher temperature.Radiation from the xenon arc source was appropriately filtered so as toprovide an excellent match to the ultraviolet portion of the solarspectrum. Samples were tested prior to any exposure to these acceleratedweathering conditions, and then removed at total UV dosage intervals ofabout 373 MJ/m² for evaluation. The number of these dosage intervals towhich the Examples were exposed are specified below.

Heat and Humidity Exposure (85/85)

For 85/85 evaluation, 4 in. (10 cm) by 6-in. (15 cm) samples were hungin a chamber at 85° F. and 85% relative humidity for 1000 hours. Thesamples were then removed from the chamber, maintained at ambientconditions for 24 hours, and then evaluated for haze, clarity, andtransmission. The procedure was repeated up to three times as specifiedbelow.

Film Examples 1 to 4 and Comparative Examples A and B

Mixtures of Copolymer Examples 1 to 5 and Copolymer 6 and, forcomparison, 2-(4,6-diphenyl-1,3,5-triazin-2-yl-)-5-((hexyl)oxyphenol and2-[4-[(2-hydroxy-3-(2′-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine(obtained from BASF, Florham Park, N.J., under the trade designations“TINUVIN 1577” and “TINUVIN 405”, respectively) were each compoundedwith PVDF (obtained from Inner Mongolia Wanhao Fluorochemical InducstryCo., Ltd., China, under the trade designation “WANHAO 906”) on a scaleof up to 85 grams in a mixer obtained from Brabender, Duisburg, Germany.The oligomers and comparative UV absorbers were added such that theactive UV absorbers made up 2% by weight of the batches. Oligomers wereadded at 10% by weight to provide 2% by weight of the active UVabsorbing monomeric unit in the batch. The compounded mixtures were hotpressed typically into 7 mil (0.18 mm thick) film patches.

Haze and clarity were measured according to the methods described above,and average transmission over a range from 400 nm to 1150 nm weremeasured using a spectrophotometer (a “LAMBDA 900” Spectrophotometerobtained from Lambda Scientific, Edwardstown, SA, Australia) initiallyand after Accelerated Ultraviolet Light Exposure for a total of threeintervals and Heat with Humidity (85/85) for a total of three cycles forFilm Examples 1 to 3. For Film Example 4, two exposure intervals forAccelerated Ultraviolet Light Exposure and two exposure cycles to Heatand Humidity were carried out. The results are shown in Table 5, below.

TABLE 5 Control Film (100% Comp. Ex. 1 Comp. Ex. 2 Film Ex. 1 Film Ex. 2Film Ex. 3 Film Ex. 4 Example PVDF) “TINUVIN “TINUVIN CopolymerCopolymer Copolymer Copolymer UVA none 405” 1577” Ex. 1 Ex. 2 Ex. 3 6Initial Haze % 36.1 97.1 100 61.4 65.4 47.0 38.2 85/85 Haze % 53.0 99.2101 64.4 62.2 52.0 37.1 UV Exp. Haze % 41.7 97.6 101 62.2 53.7 54.1 27.4Initial Clarity % 95.1 74.6 72.6 93.6 86.3 87.1 96.7 85/85 Clarity %91.8 63.9 19.9 92.8 74.0 85.4 94.6 UV Exp. Clarity % 93.5 65.7 64.2 91.283.3 86.0 96.2 Initial Ave T % 92.6 82.7 68.3 82.2 87.7 92.9 91.2 85/85Ave T % 92.6 75.0 61.3 75.0 88.6 86.1 86.8 UV Exp. Ave T % 92.55 80.063.3 92.9 92.6 85.7 90.6

Copolymer Examples 1 to 5 and Copolymer 6 were extrusion compounded withPVDF homopolymer (obtained from Inner Mongolia Wanhao FluorochemicalIndustry Co., Ltd., China, under the trade designation “WANHAO 906”)using a 25 mm twin screw extruder obtained from KraussMaffei Berstorff(Hannover, Germany) and pelletized into PVDF-UVA masterbatch pellets atthe extrusion rates and process conditions shown in Table 6. Thecopolymers were included such that the composition included thecopolymers at 4 percent by weight, based on the weight of thecomposition. For each extrusion, the temperature was 400° F. to 475° F.(204° C. to 246° C.).

TABLE 6 Copolymer Copolymer Copolymer Copolymer Copolymer UVA Ex. 2 Ex.1 Ex. 3 6 Ex. 4 PVDF rate in 4.0 (1.8) 4.0 (1.8) 4.0 (1.8) 8.0 (3.6) 4.0(1.8) lbs/hr (kg/hr) UVA rate in  1.0 (0.45)  1.0 (0.45)  1.0 (0.45) 2.0 (0.91)  1.0 (0.45) lbs/hr (kg/hr) Extruder Screw 203  203  254  354254  Speed (rpm) Polymer Melt 486 (252) 475 (246) 472 (244) 468 (242)469 (243) temperature in ° F. (° C.) Extruder Gate 40 (2.8 × 10⁵) 36(2.5 × 10⁵) 48 (3.8 × 10⁵) 78 (5.4 × 10⁵) 50 (3.4 × 10⁵) Pressure in psi(Pa) Extruder Amps 13 13 14  18 16 Extruder Volts 77 77 96 134 96

For comparison, a triazine UV absorber obtained from BASF under thetrade designation “TINUVIN 1600” was also extrusion compounded into PVDFat similar process conditions as shown above. These comparative polymerstrands were very hazy and difficult to pelletize.

The masterbatch pellets made as shown in Table 6 were extrusioncompounded with PVDF homopolymer obtained from 3M Company, St. Paul,Minn. under the trade designation “DYNEON 6008” and extruded into 50micrometer thick film using a 25 mm single screw extruder obtained fromDavis-Standard, Pawcatuck, Conn., having an extruder screw designed witha Maddock Mixer. The extrusion rates and process conditions were asshown in Table 7. Again, the final UVA wt % in the film referred to inTable 7 refers to the wt % of the active UV absorbing unit in theoligomer. Oligomers were added at 10% by weight to provide 2% by weightof the active UV absorbing monomeric unit in the film, 5% by weight toprovide 1% by weight of the active UV absorbing monomeric unit in thefilm, and so on.

TABLE 7 PVDF UVA MB Final Extruder Rate, Rate, UVA Screw Line PVDFlbs/hr lbs/hr wt % in Speed Speed Type UVA Type (kg/hr) (kg/hr) Film(rpm) (fpm) Comp. None 10 (4.5)  10 (4.5) 0.0 46 26 Ex. 3 Film Ex.Copolymer 10 (4.5)  10 (4.5) 2.0 46 26 5 Example 3 Film Ex. Copolymer 10(4.5)  10 (4.5) 2.0 46 26 6 Example 1 Film Ex. Copolymer 10 (4.5)  10(4.5) 2.0 46 26 7 Example 4 Film Ex. Copolymer 10 (4.5)  10 (4.5) 2.0 4626 8 Example 2 Film Ex. Copolymer 6 10 (4.5)   5 (2.3) 1.0 46 26 9Copolymer   5 (2.3) 1.0 Example 4 Film Ex. Copolymer 10 (4.5)   5 (2.3)1.0 46 26 10 Example 2 Copolymer 6   5 (2.3) 1.0 Film 11 Copolymer 6 10(4.5)  10 (4.5) 2.0 46 26 Film Ex. Copolymer 10 (4.5)   5 (2.3) 0.8 4626 12 Example 2 Copolymer 4 2.5 (1.1) 0.4 Copolymer 6   5 (2.3) 0.8

Film Examples 5 and 8 were non-uniform in color, haze, and had numerousholes. The addition of Copolymer 6 provided surprisingly good qualityFilm Example 10, which had uniform color, haze, and flat caliper.

Average transmission over a range from 250 nm to 2500 nm for ComparativeExample 3 and Film Examples 6, 7, 9, and 12 and Film 11 were measuredusing a “LAMBDA 950” Spectrophotometer obtained from Lambda Scientificbefore and after Accelerated Ultraviolet Light Exposure for threeintervals according to the method described above. The results are shownin Table 8, below.

TABLE 8 Avg. Transmission Avg. Transmission Avg. Transmission 400 nm-800nm (%) 400 nm-500 nm (%) 300 nm to 395 nm (%) Film Example initial 3intervals initial 3 intervals initial 3 intervals Comp. Ex. 3 90.3 89.089.9 87.2 66.4 61.6 Film Ex. 6 84.8 85.5 81.3 82.3 14.7 20.1 Film Ex. 789.3 88.2 13.5 Film Ex. 9 88.8 89.2 87.2 88.1 15.0 23.1 Film Ex. 12 88.888.1 87.2 86.7 15.5 25.8 Film 11 88.9 90.2 87.3 89.3 18.7 30.1

Film Example 13

Film Example 13 was made using the method of Film Examples 1 to 4 exceptusing Copolymer Example 5 as the copolymer. Films were made having athickness of about 3.5 to 3.6 mils (0.089 to 0.091 mm) Table 9 belowshows transmission, haze, and clarity data for 2 samples of Film Example13 13 initially and after one interval of Accelerated Ultraviolet LightExposure. The methods described in Film Examples 1 to 4 above were used.

TABLE 9 % Transmission 400-1150 nm % Haze % Clarity Initial 1 intervalchange Initial 1 interval change Initial 1 interval change 1 93 93.1 065.5 66.6 1.1 83.5 79.8 −3.7 2 91.8 92.4 1.3 55.4 55.4 0 80.8 75.5 −5.3

Various modifications and alterations of this disclosure may be made bythose skilled the art without departing from the scope and spirit of thedisclosure, and it should be understood that this invention is not to beunduly limited to the illustrative embodiments set forth herein.

What is claimed is:
 1. A copolymer comprising: a first divalent unitcomprising a pendent ultraviolet absorbing group comprising a triazine;and a second divalent unit represented by formula:

wherein Rf represents a fluoroalkyl group having from 1 to 6 carbonatoms optionally interrupted by one —O— group, or Rf represents apolyfluoropolyether group; R¹ is hydrogen or methyl; Q is a bond,—SO₂—N(R)—, or —C(O)—N(R)—, wherein R is alkyl having from 1 to 4 carbonatoms or hydrogen; and m is an integer from 0 to 11, wherein thecopolymer is a thermoplastic copolymer.
 2. The copolymer of claim 1,wherein the first divalent unit is represented by formula:

wherein R¹ is hydrogen or methyl; V is O or NH; X is alkylene oralkyleneoxy group having from 1 to 10 carbon atoms and optionallyinterrupted by one or more —O— groups and optionally substituted by ahydroxyl group; R is alkyl having from one to four carbon atoms; n is 0or 1; and Z is a 4,6-bisphenyl[1,3,5]triazin-2-yl group, wherein the4,6-bisphenyl[1,3,5]triazin-2yl group, is optionally substituted by oneor more alkyl, aryl, alkoxy, hydroxyl, or halogen substituents, or acombination of these substituents.
 3. The copolymer of claim 1, whereinRf represents a perfluoroalkyl group having up to 4 carbon atoms.
 4. Thecopolymer of claim 1, further comprising a third divalent unitrepresented by formula:

wherein R⁶ is hydrogen or methyl; and R⁵ is alkyl having from 1 to 4carbon atoms.
 5. The copolymer of claim 1, wherein the second divalentunit is present in the copolymer in an amount of up to 50 percent byweight, based on the total weight of the copolymer.
 6. A compositioncomprising a fluoropolymer and the copolymer of claim
 1. 7. Thecomposition of claim 6, further comprising poly(methyl methacrylate). 8.The composition of claim 6, wherein the fluoropolymer is present in thecomposition in an amount of at least 50 percent by weight, based on thetotal weight of the composition.
 9. The composition of claim 6, furthercomprising a second copolymer comprising the first divalent unit and atleast one of the second divalent unit or a third divalent unitrepresented by formula:

wherein R⁶ is hydrogen or methyl; and R⁵ is alkyl having from 1 to 4carbon atoms.
 10. The composition of claim 9, wherein the copolymer andthe second copolymer are present in the composition in an amount up to20 percent combined weight, based on the total weight of thecomposition.
 11. The composition of claim 6, wherein the composition isessentially free of volatile organic solvent.
 12. The composition ofclaim 6, wherein the fluoropolymer is selected from the group consistingof ethylene-tetrafluoroethylene copolymer, atetrafluoroethylene-hexafluoropropylene copolymer, atetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer,or polyvinylidene fluoride.
 13. The composition of claim 6 in the formof a film.
 14. A photovoltaic device comprising the composition of claim6.
 15. The composition of claim 13, wherein the film is a multilayerfilm.
 16. A composition comprising: a fluoropolymer; a copolymercomprising: a first divalent unit comprising a pendent ultraviolentabsorbing group; and a second divalent unit represented by formula:

wherein Rf represents a fluoroalkyl group having from 1 to 6 carbonatoms optionally interrupted by one —O— group, or Rf represents apolyfluoropolyether group; R¹ is hydrogen or methyl; Q is a bond,—SO₂—N(R)—, or —C(O)—N(R)—, wherein R is alkyl having from 1 to 4 carbonatoms or hydrogen; and m is an integer from 0 to 11, wherein thecopolymer is a thermoplastic copolymer; and a second copolymer, whereinthe second copolymer is a copolymer of methyl methacrylate and anacrylate- or methacrylate-functional ultraviolet absorbing group. 17.The copolymer of claim 1, wherein the copolymer is an oligomer with anumber average molecular weight of up to 50,000 grams per mole.
 18. Thecopolymer of claim 17, wherein the oligomer has a number averagemolecular weight greater than 5000 grams per mole.
 19. The compositionof claim 16, wherein the pendent ultraviolet absorbing group comprises atriazine, a benzophenone, or a benzotriazole.
 20. The composition ofclaim 16, further comprising poly(methyl methacrylate).